fix(logging): prefer ToolkitError.trace

Problem:
When debugging/developing Toolkit, the logger logs the default nodejs
stacktrace instead of `ToolkitError.trace`. That is sub-optimal because:
1. doesn't reflect what users will see (confusing: as a developer I want
   to make sure the logs are meaningful for the user).
2. as a developer, the nodejs stacktrace is often useless anyway.

Solution:
Prefer to log `ToolkitError.trace` even if we have source mapping.

Author: justinmk3

src/shared/logger/winstonToolkitLogger.ts

@@ -119,11 +119,18 @@ export class WinstonToolkitLogger implements Logger, vscode.Disposable {
     }
 
     private mapError(level: LogLevel, err: Error): Error | string {
+        // Use ToolkitError.trace even if we have source mapping (see below), because:
+        // 1. it is what users will see, we want visibility into that when debugging
+        // 2. it is often more useful than the stacktrace anyway
+        if (err instanceof ToolkitError) {
+            return err.trace
+        }
+
         if (isSourceMappingAvailable() && level === 'error') {
             return err
         }
 
-        return err instanceof ToolkitError ? err.trace : formatError(UnknownError.cast(err))
+        return formatError(UnknownError.cast(err))
     }
 
     private writeToLogs(level: LogLevel, message: string | Error, ...meta: any[]): number {